Our research efforts will be focused on a study of the effect of donor age on the transplantability of islets of Langerhans into diabetic, recipient rats. Lazarow reported and we confirmed the observation that islets of very young donors can improve the diabetic process when they are implanted into diabetic animals whereas islets of older donors lose this ability. Functional and structural properties of these islets were investigated in our laboratory and were found to be identical, regardless of donor age. Several workers have previously reported that collagenase treatment of islets leads to the destruction of membrane receptors required for somatostatin action. Acutely isolated islets are therefore resistant to somatostatin action. Incubation of these islets in enriched culture medium permits regrowth of these receptors and responsivity to somatostatin action is restored to normal. We initiated electron microscopic, concanavalin A binding studies to the membranes of acutely isolated and incubated islets. This plant lectin binds avidly to glycoprotein moieties in the cellular membrane. Binding studies will be correlated with functional properties of both acutely isolated and with incubated islets. BIBLIOGRAPHIC REFERENCES: Chez, R.A., Mintz, D.H., Reynolds, W.A. and Hutchinson, D.L.: Maternal-fetal plasma glucose relationships in late monkey pregnancy. Amer. J. Ob. and Gyn. 121:938-940, 1975. Fleischman, A.R., Lerman, S., Oakes, G., Epstein, M., Chez, R.A. and Mintz, D.H.: Perinatal primate parathyroid hormone metabolism. Biol. of the Neonate 27: 40-49, 1975.